1. Field of the Invention
The present invention relates to a circuit structure, and more particularly to a circuit structure and process thereof.
2. Description of Related Art
The kinds of circuit boards normally used inside an electronic apparatus include the rigid circuit board and the flexible circuit board. The dielectric layer of a rigid circuit board is made from a strong and tough material for carrying and electrically connecting electronic components located on a single plane. The dielectric layer of a flexible circuit board is made from a flexible material for electrically connecting two electronic components located on different planes. Due to spatial limitation or other factors, the rigid circuit board and the flexible circuit board may be combined and applied together.
Conventionally, the techniques for fabricating a rigid circuit board (from now on, the circuit board) include the lamination process and the build-up process.
In the lamination process, circuit patterns are separately fabricated on dielectric layers. The circuit patterns, the dielectric layers on which the circuit patterns are disposed, and a dielectric layer for connection are aligned and pressed in a single operation to form the circuit board. Next, a conductive through via process is performed to fabricate conductive through vias for electrically connecting the circuit patterns located in different layer counts.
In the build-up process, circuit patterns and dielectric layers are alternately fabricated on a core in sequence. In addition, conductive blind via processes are also performed in the process of fabricating the circuit patterns and the dielectric layers so that conductive blind vias for connecting the circuit patterns in different layer counts are formed.
Regardless of whether the lamination process or the build-up process is used, the conductive via process fabricates a conductive via by forming an opening in a single operation and then filling the opening with conductive material. However, this method of performing a single operation to form each opening is disadvantageous to fabricating a conductive via with a high aspect ratio.